For women, that slight - or sometimes not so slight twisting pain you feel in the middles if your menstral cycle indicating an egg was just released from the ovary. It was named after the physician who discovered its existence could be relied upon to a degree, for females who are in tune to their bodies and cycles. Of course he had to have a blizzard-O name!

Girl 1 - " oh! I just felt a quick pain right in my lower left pelvis, but now it's gone."
Girl 2 -" Are you in the middle of your cycle? Cause if you are, your ovulating & better double up on the protection or you're going to get your ass Prego! You just felt Mittlesmirtz."